YAP1 nuclear efflux and transcriptional reprograming is triggered by membrane diminution upon VSV-G-induced cell fusion

Cells in many tissues, such as bone, muscle, and placenta, fuse into syncytia to acquire new functions and transcriptional programs. While it is known that fused cells are specialized, it is unclear whether cell-fusion itself promotes programmatic changes that generate the new cellular state. To address this, we employed a fusogen-mediated, cell-fusion system to create syncytia from undifferentiated cells. RNA-seq analysis revealed cell-fusion initiates dramatic transcriptional changes. To gain mechanistic insights, we measured plasma membrane surface area after cell-fusion and found it diminished through increased endocytosis. Consequently, glucose transporters are internalized, and cytoplasmic glucose and ATP transiently decrease. This reduced energetic state activates AMPK, which inhibits YAP1, causing extensive transcriptional- reprogramming and cell-cycle arrest. Impairing either endocytosis or AMPK activity prevents YAP1 inhibition and cell-cycle arrest after fusion. Together, these data demonstrate plasma membrane diminishment upon cell-fusion causes transient nutrient stress that promotes transcriptional-reprogramming independent from extrinsic cues. Eight total samples of SUM-159 cells were analyzed using RNA-seq. There are four replicates of control cells and four replicates of VSV-G mediated fused cells